I am starting this thread to discuss various battery aging models. Surfingslovak developed a battery aging model referenced in the Wiki:

http://bit.ly/leafbatterydegradationmodel

Since some of the numbers didn't fit with Nissan's claims (even after they mentioned the "glideslope" in Arizona to 76% battery capacity remaining, and the fact that only 7500 miles were assumed for Arizona), I decided to see if I could tweak the model to fit TickTock's graph:

Here are my results (you may have to make text smaller in browser to fit on screen):

Summary:

Model fits the data from Nissan quite well using following assumptions:

Calendar loss first year without aging factor - 6.5%

Calendar loss slows with square root of time

Cycling loss per 12500 miles without aging factor - 1.5%

Cycling loss is linear

Boston aging factor adjusted to 0.75

"Normal" aging factor adjusted to 0.90

Phoenix aging factor adjusted to 1.35

Aging factors relative to "Normal" are:

Boston - 0.83

Normal - 1.00

Phoenix - 1.50

Note: while it might seem that my selections were random, or that many combinations could give the same results, I found that changing any of the values from this set of numbers caused increasing errors in predicting the numbers found on the graph. I make no claim that these numbers are good predictions of reality, only that they fit Nissan's figures closely. Comments, discussion, suggestions for improvement, etc. are welcome. If anyone wants to play with the actual spreadsheet, let me know.